Power must be supplied with minimal power consumption to circuits that retain and/or operate on data when an integrated circuit device is in a sleep mode. These circuits are powered so as to retain the data when other circuits of the integrated circuit device are in a low power sleep mode. In addition, minimal dynamic power may be supplied to circuits that operate on data during the sleep mode, e.g., a real time clock and calendar (RTCC), at minimum power consumption.
A primary voltage regulator having precision voltage regulation, e.g., a bandgap voltage reference and associated voltage regulator circuits, requires a significant amount of power that is not desirable when battery operated devices go into a low power sleep mode yet still have to maintain voltage(s) on some circuits in order to retain/operate on data.